JPH023706A - Clutch tightening mechanism of automatic transmission - Google Patents

Abstract

PURPOSE:To improve productivity and shorten the dimension in the axial direction by making the effective diameter of the second piston less than the diameter of the first piston and accommodating the slidable surface between the both pistons inside the slidable surface between the first piston and a drum. CONSTITUTION:The first piston 21 is fitted in slidable ways between the parallel parts 20a and 20b of a drum 20, and one edge of the second piston 22 is joined with the parallel part 20b by a snap ring 23, and the other edge is attached in slidable ways onto the slidable part 21a inside the first piston 21. The effective diameter L2 of the second piston 22 is made less than the effective diameter L1 of the first piston 21. Therefore, the clutch tightening/releasing function is secured, and the simple shape of the first piston 21 is obtained, and productivity can be improved, and the dimension in the axial direction of the whole can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a clutch engagement mechanism for an automatic transmission used in a power transmission mechanism of a vehicle.

(Prior art) As a clutch for this type of conventional automatic transmission, for example, Z
F (ZAIINRAD FAIIRIK FRI[D
RICIISHAFl! 4HP1 manufactured by N., West Germany)
There is a low clutch for the Type 4 automatic transmission, and its main parts are shown in Figure 2.

In the figure, lO is a drum, and its parallel parts 10a and 10b
A first piston 11 is fitted in between so as to be slidable in the axial direction. Here, the parallel part 10b of the drum IO has a second
One end of the piston 12 is coupled to the second piston 1
The other end of the piston 2 is in contact with the sliding portion 11a of the first piston 11. Further, the tip of the sliding portion 11a is in contact with the clutch plate 13.

The space surrounded by the drum IO and the first piston 11 defines a first oil chamber 14, and the parallel part 10b of the drum 10,
A space surrounded by the first piston 11 and the second piston 12 defines a second oil chamber 15.

In this clutch, when clutch pressure PC is supplied to the first oil chamber 14, the first piston 11 slides and its end presses the clutch plate 13 to engage the clutch. When the pressure P is released, the first piston 11 slides from the clutch plate 13 in the clutch release direction due to the spring force of a spring (not shown) provided in the second oil chamber 15, thereby releasing the clutch.

(Problem to be Solved by the Invention) However, in the conventional clutch described above, the effective diameter (Ll) of the second piston 11 is larger than the effective diameter (Ll) of the first piston 11.
Since the effective diameter (L) of 2 is configured to be large (t, + < t, z), the sliding part 11a of the first piston 11 with the second piston 12 and the sliding part with the drum 10 are inevitably 11
b must be arranged in parallel in the axial direction so that their sliding parts do not overlap each other, and as a result, the shape of the first piston becomes complicated and the axial dimension of the entire clutch becomes undesirable. There was a problem that the amount of water increased. Since the installation space in the engine compartment of a vehicle is limited, this problem significantly impedes the degree of freedom in designing the arrangement of parts in the engine compartment, especially in FF (front wheel drive) vehicles.

(Means for Solving the Problems) The present invention attempts to solve the above-mentioned problem by making the effective diameter of the second piston smaller than that of the first piston, and the second piston is fitted to the drum so as to be slidable in the axial direction. In the clutch engagement mechanism for an automatic transmission, the effective diameter of the second piston is set to the first piston, and the second piston has one end fixed to the drum and the other end contacting the first piston. The diameter of the piston is smaller than that of the piston, and the sliding surface between the first and second pistons is accommodated inside the sliding surface between the first piston and the drum.

(Function) In the clutch engagement mechanism of the present invention, the effective diameter (shi) of the second piston is improved to be smaller (t, +>t, z) than the effective diameter (L, ) of the first piston. Since the,
The sliding surface of the first piston with the second piston overlaps the sliding surface of the first piston with the drum in the axial direction,
It can be configured to be housed inside the sliding surface.

When configured in this way, the clutch engagement and release functions equivalent to those of the conventional example described above are sufficiently ensured, and the shape of the first piston is simplified to improve manufacturability.
- By shortening the axial distance between the second pistons, the axial dimension of the entire clutch can be shortened to the extent that the degree of freedom in designing the arrangement of parts in the engine room of the vehicle can be significantly improved.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram illustrating the overall configuration of a clutch engagement mechanism for an automatic transmission according to the present invention. 20 in the figure is a drum;
A first piston 21 is fitted between the parallel portions 20a and 2Ob so as to be slidable in the axial direction.

Here, a second piston 22 is provided in the parallel portion 20b of the drum 20.
One end of the second piston 22 is connected by a snap ring 23, and the other end of the second piston 22 is connected to the sliding part 21 of the first piston 21.
It is in contact with a. Further, the tip of the sliding portion 21a is in contact with the clutch plate 24.

The space surrounded by the drum 20 and the first piston 21 defines a first oil chamber 27 together with the seals 25 and 26, and the parallel part 20b1 of the drum 20 and the first piston 21 and the second
The space surrounded by the piston 22 defines a second oil chamber 29 together with the seal 28 . Note that the first piston 21 is provided with an oil passage 21b that communicates between the first oil chamber and the second oil chamber, and a ball 30 is fitted into the oil passage 21b so as to be slidable in the axial direction. be. Also, near the snap ring 23 of the second piston 22, there is a hole 22a for oil circulation in the second oil chamber.
and an oil catch 31 are provided, and a second oil chamber 29
A spring 32 is provided in the axial direction.

The biggest difference between this example and the conventional example is that the effective diameter L2 of the second piston is smaller than the effective diameter of the first piston, thereby making the entire clutch engagement mechanism compact. This clutch engagement mechanism extremely smoothly engages and releases the clutch as described below.

That is, first, when the clutch is engaged, the first oil chamber 27
When the clutch pressure Pc is supplied to the oil passage 21b, the ball 30 in the oil passage 21b has a check function to cut off communication between the oil chambers 27 and 29. As a result, the first piston 21 strokes in the engagement direction against the spring 32, so that the end of the piston 21 presses the clutch plate 24 to engage the clutch, and power is transmitted in the automatic transmission. At this time, the oil in the second oil chamber 29 is discharged from the hole 22a of the second piston 22.

On the other hand, when the clutch is released, the second oil chamber 29 compressed by the stroke of the piston 21 is filled with oil collected by the oil catch 31 and introduced from the hole 22a. A force is generated by the spring force that tends to move the first piston 21 in the releasing direction. In this state, when the clutch pressure P, is reduced to zero to release the clutch, the clutch pressure reaches the predetermined oil pressure P,.

When the oil pressure P,. Ball 3 due to centrifugal force that overcomes
0 opens the oil passage 21b and allows the oil chambers 27 and 29 to communicate with each other. As a result, oil flows from the oil chamber 27 to the oil chamber 29, rapidly reducing the oil pressure in the first oil chamber 27, and at the same time, the oil that has flowed in is discharged from the hole 22c, reducing the amount of oil in both sleeve chambers to the oil catch 31. The hydraulic pressure in both arm chambers is made equal by the amount determined by the surrounding space. At this time, the above-mentioned centrifugal hydraulic pressure and the spring force of the spring 32 cause the first piston 21 to stroke in the releasing direction, thereby releasing the clutch.

In this way, the axial dimension of the entire clutch can be shortened while sufficient clutch engagement and release functions are ensured.

In this example, a ball 30 is provided in the oil passage 21b, and this ball 30 allows the oil flowing from the ball hole to flow into the second hydraulic chamber 27 until the hydraulic pressure is activated when the hydraulic pressure rises in the first hydraulic chamber 27.
Since it is stored in the hydraulic chamber 29, when centrifugal hydraulic pressure is generated in the hydraulic chamber 27, the centrifugal hydraulic pressure canceling mechanism that cancels it quickly operates, stabilizing the shifting characteristics of the automatic transmission to the desired characteristics. You can also obtain the effect of

(Effects of the Invention) As described above, in the clutch engagement mechanism for an automatic transmission of the present invention, the effective diameter of the second piston is made smaller than that of the first piston, and the sliding surface between the first piston and the second piston is made smaller than the first piston. Since it is configured to be housed inside the sliding surface between the piston and the drum, it ensures sufficient clutch engagement and release functions, while
The shape of the first piston is simplified to improve manufacturability, and the axial dimension of the entire clutch is shortened by the shortened axial distance between the first and second pistons, making it a component in the engine compartment of the vehicle. The degree of freedom in design of arrangement can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the overall configuration of a clutch engagement mechanism for an automatic transmission according to the present invention, and FIG. 2 is a diagram illustrating the configuration of main parts of a conventional clutch. 10, 20...Drums 10a, 10b, 20a, 20b...Parallel part 1
1, 21--first piston lla, llb, 2
1a...Sliding part 21b...Oil passage 12
．． 22... Second piston 22a... Hole
13.24...Clutch plate 14, 27...First oil passage 15.29...Second oil passage 23...Snap ring 25.26.28...Seal 30...Ball 31. ...Oil catch 32...
Spring diagram 2

Claims (1)

[Claims] 1. A first member fitted to the drum so as to be slidable in the axial direction.
In a clutch engagement mechanism for an automatic transmission comprising a piston and a second piston having one end fixed to the drum and the other end contacting the first piston, the effective diameter of the second piston is smaller than the diameter of the first piston. 1. A clutch engagement mechanism for an automatic transmission, characterized in that the clutch is made smaller so that a sliding surface between the first and second pistons is housed inside a sliding surface between the first piston and the drum.